Luteinizing hormone and progesterone concentrations and induction of estrus after use of norgestomet ear implants or constant infusion of gonadotropin-releasing hormone in anestrous, nonlactating dairy goats

K. N. Bretzlaff From the Department of Large Animal Medicine and Surgery, Texas A&M University, College Station, TX 77843 (Bretzlaff, Scarfe, Elmore, Varner) and the International Dairy Goat Research Center, Prairie View A&M University, Prairie View, TX 77446 (Nuti, Capehart) and the Department of Veterinary Biosciences, University of Illinois, Urbana, IL 61801 (Weston).

Search for other papers by K. N. Bretzlaff in
Current site
Google Scholar
PubMed
Close
 DVM, PhD
,
L. C. Nuti From the Department of Large Animal Medicine and Surgery, Texas A&M University, College Station, TX 77843 (Bretzlaff, Scarfe, Elmore, Varner) and the International Dairy Goat Research Center, Prairie View A&M University, Prairie View, TX 77446 (Nuti, Capehart) and the Department of Veterinary Biosciences, University of Illinois, Urbana, IL 61801 (Weston).

Search for other papers by L. C. Nuti in
Current site
Google Scholar
PubMed
Close
 PhD
,
A. D. Scarfe From the Department of Large Animal Medicine and Surgery, Texas A&M University, College Station, TX 77843 (Bretzlaff, Scarfe, Elmore, Varner) and the International Dairy Goat Research Center, Prairie View A&M University, Prairie View, TX 77446 (Nuti, Capehart) and the Department of Veterinary Biosciences, University of Illinois, Urbana, IL 61801 (Weston).

Search for other papers by A. D. Scarfe in
Current site
Google Scholar
PubMed
Close
 DVM, PhD
,
R. G. Elmore From the Department of Large Animal Medicine and Surgery, Texas A&M University, College Station, TX 77843 (Bretzlaff, Scarfe, Elmore, Varner) and the International Dairy Goat Research Center, Prairie View A&M University, Prairie View, TX 77446 (Nuti, Capehart) and the Department of Veterinary Biosciences, University of Illinois, Urbana, IL 61801 (Weston).

Search for other papers by R. G. Elmore in
Current site
Google Scholar
PubMed
Close
 DVM, MS
,
J. Capehart From the Department of Large Animal Medicine and Surgery, Texas A&M University, College Station, TX 77843 (Bretzlaff, Scarfe, Elmore, Varner) and the International Dairy Goat Research Center, Prairie View A&M University, Prairie View, TX 77446 (Nuti, Capehart) and the Department of Veterinary Biosciences, University of Illinois, Urbana, IL 61801 (Weston).

Search for other papers by J. Capehart in
Current site
Google Scholar
PubMed
Close
 MS
,
D. D. Varner From the Department of Large Animal Medicine and Surgery, Texas A&M University, College Station, TX 77843 (Bretzlaff, Scarfe, Elmore, Varner) and the International Dairy Goat Research Center, Prairie View A&M University, Prairie View, TX 77446 (Nuti, Capehart) and the Department of Veterinary Biosciences, University of Illinois, Urbana, IL 61801 (Weston).

Search for other papers by D. D. Varner in
Current site
Google Scholar
PubMed
Close
 DVM, MS
, and
P. G. Weston From the Department of Large Animal Medicine and Surgery, Texas A&M University, College Station, TX 77843 (Bretzlaff, Scarfe, Elmore, Varner) and the International Dairy Goat Research Center, Prairie View A&M University, Prairie View, TX 77446 (Nuti, Capehart) and the Department of Veterinary Biosciences, University of Illinois, Urbana, IL 61801 (Weston).

Search for other papers by P. G. Weston in
Current site
Google Scholar
PubMed
Close
 PhD

Click on author name to view affiliation information

Summary

Plasma luteinizing hormone and progesterone concentrations, time to onset of estrus, and pregnancy rates were determined in nonlactating anestrous does given 1 of 4 treatments: subcutaneous ear implants containing 3 mg of norgestomet for 9 days (nor; n = 6); subcutaneous administration, using osmotic minipumps, of 250 ng of gonadotropin-releasing hormone (GnRH)/h for 48 hours (GnRH; n = 6); 3 mg of nor for 9 days, followed immediately by 250 ng of GnRH/h for 48 hours (nor + GnRH; n = 6); or no treatment (control; n = 6). During the 72-hour period after removal of nor or insertion of GnRH pumps, 6 of 6, 0 of 6, 6 of 6, and 3 of 6 does were observed in estrus at a mean (± se) of 49 (± 3.0), 0(± 0), 32 (± 2.0), and 35 (± 13.8) hours in groups nor, GnRH, nor + GnRH, and control, respectively. Time from end of treatment to peak concentrations of luteinizing hormone were 56 ± 4.0, 28 ± 4.7, 34 ± 4.3, and 41 ± 9.7 hours (mean ± se) for nor, GnRH, nor ± GnRH, and control, respectively. Peak concentrations of luteinizing hormone were significantly greater and occurred significantly later in does given nor. Progesterone concentrations in does that became pregnant increased to concentrations ≥ 1.0 ng/ml 3 to 5 days after breeding and remained high.

Functional corpora lutea (cl) was found in 6 does that did not become pregnant, 1 cl was associated with pseudopregnancy and 1 cl was associated with ovulation prior to placement of the GnRH pumps. Functional cl failed to form in 10 of the 12 does in groups GnRH and control. Does had either continual low concentrations of progesterone (3 does) or short-term increases in concentrations of progesterone (7 does). Conception rates for does in groups nor, GnRH, nor + GnRH, and control were 83%, 0%, 50% and 0%, respectively. Four does given GnRH and 3 control does were observed in estrus and were bred during the subsequent 2-week period. All of these does, except 1 control became pregnant subsequent to these breedings.

The treatments nor and nor + GnRH were effective in inducing a synchronized estrus in dairy goats. However, the use of bucks to detect estrus may have introduced the buck effect and enhanced the performance of nor alone, which has not been this effective in other studies with small ruminants.

Summary

Plasma luteinizing hormone and progesterone concentrations, time to onset of estrus, and pregnancy rates were determined in nonlactating anestrous does given 1 of 4 treatments: subcutaneous ear implants containing 3 mg of norgestomet for 9 days (nor; n = 6); subcutaneous administration, using osmotic minipumps, of 250 ng of gonadotropin-releasing hormone (GnRH)/h for 48 hours (GnRH; n = 6); 3 mg of nor for 9 days, followed immediately by 250 ng of GnRH/h for 48 hours (nor + GnRH; n = 6); or no treatment (control; n = 6). During the 72-hour period after removal of nor or insertion of GnRH pumps, 6 of 6, 0 of 6, 6 of 6, and 3 of 6 does were observed in estrus at a mean (± se) of 49 (± 3.0), 0(± 0), 32 (± 2.0), and 35 (± 13.8) hours in groups nor, GnRH, nor + GnRH, and control, respectively. Time from end of treatment to peak concentrations of luteinizing hormone were 56 ± 4.0, 28 ± 4.7, 34 ± 4.3, and 41 ± 9.7 hours (mean ± se) for nor, GnRH, nor ± GnRH, and control, respectively. Peak concentrations of luteinizing hormone were significantly greater and occurred significantly later in does given nor. Progesterone concentrations in does that became pregnant increased to concentrations ≥ 1.0 ng/ml 3 to 5 days after breeding and remained high.

Functional corpora lutea (cl) was found in 6 does that did not become pregnant, 1 cl was associated with pseudopregnancy and 1 cl was associated with ovulation prior to placement of the GnRH pumps. Functional cl failed to form in 10 of the 12 does in groups GnRH and control. Does had either continual low concentrations of progesterone (3 does) or short-term increases in concentrations of progesterone (7 does). Conception rates for does in groups nor, GnRH, nor + GnRH, and control were 83%, 0%, 50% and 0%, respectively. Four does given GnRH and 3 control does were observed in estrus and were bred during the subsequent 2-week period. All of these does, except 1 control became pregnant subsequent to these breedings.

The treatments nor and nor + GnRH were effective in inducing a synchronized estrus in dairy goats. However, the use of bucks to detect estrus may have introduced the buck effect and enhanced the performance of nor alone, which has not been this effective in other studies with small ruminants.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 44 44 10
PDF Downloads 33 33 8
Advertisement